ALL ABOUT OIL
HOW OIL GETS INTO THE OCEAN Large events like the Deepwater Horizon and Ixtoc oil spills are rare (although not rare enough), but oil has several more frequent ways of moving into the ocean. It is naturally released into the ocean by seeping through bottom sediments. Also, small spills regularly impact various parts of the Gulf of Mexico ecosystem. In Louisiana, 1500 events per year spill 330,000 gallons of Aerial dispersant application, May 5, 2010. U.S. Air Force, public domain. oil (Louisiana Oil Spill Coordinator’s Office). This fact sheet describes how three Gulf of Mexico ecosystems BARRIER ISLAND ECOSYSTEMS are affected by crude oil and some of the challenges we Washed up, weathered oil is easier to collect on sand face in cleaning oil from these habitats. beaches than in water. Machines help with oil removal. Oil biodegrades rapidly when exposed to the elements PROPERTIES OF OIL IN THE ENVIRONMENT on beaches. However, oil is often buried in the sand, Oil produced in different locations has different which preserves it for future exposure. properties. The oil released during the Deepwater Horizon Oil Spill was Louisiana Sweet Crude Oil. Sweet oil contains little sulfur, while sour oil has high sulfur content. Sweet oil is more valuable because sulfur reduces the effective energy content of the oil and damages pipelines. Louisiana Sweet is also a light oil, which means it has lower density and flows freely at room temperature. Light oil is more valuable than heavy (denser) oil because refining it produces a higher Oil approaching beach on Chandeleur Islands, La, 2010. Stewart Long, Grass percentage of gasoline and diesel fuel. Contact with Roots Mapping, creative commons. water or air causes crude oil to weather, a process that changes its chemical composition and removes some of DEEP‐WATER OCEAN ECOSYSTEMS the most toxic components. Dispersant use during the Deepwater Horizon spill caused some oil to be deposited in sediment below the DISPERSANT USE Gulf of Mexico. This prevented the oil from washing ashore and protected beaches and coastal ecosystems, A dispersant (shown in green but the effects of oil and dispersants on deep water in the figure) includes parts ecosystems are unknown. Scientists are studying these that attach to oil (a detergent, effects. shown in pink) and parts that
attach to water. Dispersants have been spread on or near COASTAL/SALT MARSH ECOSYSTEMS the ocean’s surface in past oil Oil can damage salt marshes by killing vegetation that spills because they help break holds sediment in place, leading to marsh loss. Efforts to up the oil slick as shown in clean the fragile ecosystems may cause more damage the figure. This increases the than leaving the oil would. Allowing oil to degrade on rate of microbial degradation its own is an option that must be considered when and spreads some marshes are oiled.
components of the oil through the depth of water. During the Deepwater Horizon Oil Spill dispersant was applied at a depth of Dahlia88, 2012, creative commons. about 1500 m (~5000 ft). Dispersants are toxic and scientists are exploring the effect of dispersants and the Oiled marsh in Mississippi Sound, 2010. Chris Snyder, GCRL, used by combination of dispersants and oil on organisms. permission.
OIL SPILLS AROUND THE WORLD 1999 Kuwait Oil Wells, Gulf War Location: Persian Gulf, Iraq/Iran 1978 Amoco Cadiz Released: Estimated at 168-252 million gallons (637-954 Location: Brittany, France million liters) Released: ~67 million gallons (255 million liters) Composition: Iran Light Crude (average sulfur, density) Composition: Medium Arabian Crude (sour, light) Claimed Impacts: 240 miles of Persian Gulf coastline “beyond Reported Impact: Mousse slicks covering 125 miles of coast. repair.”
Oiled beach, 1978. NOAA (http://response.restoration.noaa.gov/index.php), public domain.
1979 Ixtoc I Plumes of smoke from Kuwait oil well fires, 1991. NASA, public domain. Location: Bahia de Campeche, Mexico Released: 126 million gallons (477 million liters) 1970-2000 Niger River Delta Composition: Mexico-Maya Crude (very sour, light) Location: Nigeria Corexit 9527 used Released: 7,000 major spills released estimated 2.4 million tons Impacts: Widespread pollution of estuaries and coastal Composition: Nigeria Bonny Light (very sweet, light) lagoons; eliminated ghost crabs from large area. Claimed Impacts: Reduced life expectancy (40-years) among residents of rural communities that use river water.
2010 BP Deepwater Horizon Location: Northern Gulf of Mexico, United States Released: 210 million gallons (795 million liters) Dispersant: Corexit 9500/9527, 1.8 million gallons (6.8 million liters) Composition: Louisiana Sweet Crude (very sweet, light), Impacts: Data are still being collected regarding impacts to human and animal health and coastal and deep-water ecosystems. Adverse effect on seafood industry and tourism Ixtoc I oil well fire after the platform sank, Bay of Campeche, Mexico. from Texas to Florida. NOAA (http://response.restoration.noaa.gov/index.php), public domain.
1989 Exxon Valdez Location: Prince William Sound, Alaska Released: 11-32 million gallons (41-119 million liters) Composition: Prudhoe Bay Crude (heavy) Impacts: Large number of animal kills.
Fire on the Deepwater Horizon rig, 2010. U.S. Coast Guard, public domain.
REFERENCES State of Florida. Oil Spill Academic Task Force. Description of the MC252 crude oil. http://oilspill.fsu.edu/images/pdfs/mc-252crude-oil-desc.pdf. Retrieved 12/17/2013. Cleaning beaches after tanker Valdez ran aground, 1989, public domain. Louisiana Oil Spill Coordinator’s Office. Public Safety Services. http://www.losco.state.la.us/about.html. Retrieved 12/17/2013. Spill estimates from Wikipedia, retrieved 12/17/2013: http://en.wikipedia.org/wiki/Deepwater_Horizon_oil_spill.